Abstract: This is a zirconium-hafnium separation process utilizing a complex of zirconium-hafnium chlorides and phosphorus oxychloride. The complex is introduced into a distillation column and a hafnium chloride enriched stream is taken from the top of the column and a zirconium chloride enriched stream is taken from the bottom of the column. In particular, the invention utilizes prepurification of the zirconium-hafnium chlorides prior to introduction of the complex into the distillation column to substantially eliminate iron chloride; thus, the buildup of iron chloride in the distillation column is substantially eliminated and the column can be operated in a continuous stable, and efficient manner.

Abstract: Distillative Freezing Process is an energy conserving process for separating mixtures and superpurifying chemicals. The wet and dry distillative freezing process disclosed represents a major improvement to the distillative freezing technology and has significantly broadened its application field: the drying-up temperature and pressure are significantly higher than those of the corresponding direct dry process and a major fraction of low volatility impurities in the feed can also be removed. A basic wet and dry distillative freezing process comprises (a) a first step of transforming a liquid feed mixture into a first solid-liquid mixture, denoted as K.sub.1 mixture, (b) a second step of washing the K.sub.1 mixture with a wash liquid to thereby form a second solid-liquid mixture, denoted as K.sub.2 mixture, and an impure liquid L.sub.2, and (c) a third step of subjecting the K.sub.2 mixture to a dry distillative freezing operation to thereby form a mass of refined solid phase, denoted as S.sub.

Abstract: A wet and dry distillative freezing process is provided which comprises (a) a first step of transforming a liquid feed mixture into a first solid-liquid mixture, denoted as K.sub.-1 mixture, by either a conventional freezing operation or a wet distillative freezing operation, (b) a second step of washing the K.sub.-1 mixture with a wash liquid to thereby form a second solid-liquid mixture, denoted as K.sub.o mixture, and an impure liquid L.sub.o, and (c) a third step of subjecting the K.sub.o mixture to a dry distillative freezing operation to thereby form a mass of refined solid phase, denoted as S.sub.1, and a low pressure vapor V.sub.1. Various wash liquids may be used in the crystal washing step. It is important to note that the wash liquid used does not have to be a pure liquid but may contain some volatile impurities. This is so, because the volatile impurities in the wash liquid will be taken up in the K.sub.o mixture and will be removed in the dry distillative freezing step.

Abstract: The distillative freezing process disclosed is useful in separating and purifying a mixture that contains a volatile and crystallizing component and one or more volatile and non-crystallizing components by vaporizing the volatile components from the mixture under a sufficiently reduced pressure to thereby simultaneously form a mass of solid enriched with the crystallizing component. Two components of a mixture processed are denoted as the key components: one is the crystallizing component and is denoted as B-component; the other is the non-crystallizing component present in the greatest amount and is denoted as A-component. For a mixture to be processable by the process, it is necessary that the vapor pressure ratio of the key components be within a certain range and a low pressure phase diagram of the binary system of the key components belongs to certain types of phase diagrams.

Abstract: Vaporized elemental sulfur is recovered from a gaseous stream by cooling said stream in a first heat exchanger to condense elemental sulfur and then cooling said stream in a second heat exchanger to solidify the remaining elemental sulfur. The plugging of the heat exchanger is avoided by switching the operating conditions of the two exchangers and reversing the sequence of the flow through these two heat exchangers. The process and apparatus are especially useful in treating the tail gas and the intermediate streams in the Claus process or in the modified Claus process.Instead of reversing the flow, the plugging can be avoided by using two two-zone heat exchangers. One of the heat exchangers is operated to effect the condensation of elemental sulfur in the first zone and melting the solidified sulfur deposited in the second zone. The second heat exchanger is operated to effect condensation of sulfur in the first zone and solidification of sulfur in the second zone.

Abstract: The distillative freezing process disclosed is useful in separating a mixture containing at least two volatile components, denoted respectively as A-component and B-component, by simultaneously vaporizing the two components from the mixture under a sufficiently reduced pressure to simultaneously crystallize B-component. The vapor mixture obtained is brought to a condensed state either by a simple condensation operation or a condensation-desublimation operation without being substantially pressurized. The process may be continued to completely eliminate the liquid phase and bring the mixture into the two phase solid-vapor region. Then, the solid phase is no longer contaminated by the adhering liquid phase and gives a high purity B-component on melting. The process is particularly useful in separating mixtures containing close boiling components, such as styrene-ethyl benzene mixtures, p-xylene-m-xylene mixtures and ethylene-ethane mixtures.

Abstract: A method comprises heating the material to be treated without access of air at a temperature of 700.degree. to 800.degree. C. for a period of 1-2 hours, and then subjecting this material to subsequent magnetic separation.It is advisable that the furnace walls surrounding the material under treatment be heated to a temperature which is 100.degree. C. to 200.degree. C. higher than the boiling temperature of the volatile components of the material. Upon completion of the heating operation, the material being treated is cooled at a rate of 2 to 4 deg. per minute, whereafter iron sulphides are removed therefrom by means of magnetic separation, the intensity of magnetic field ranging from 1000 to 2000 oersted, and then copper sulphides are separated, with the field intensity ranging from 4500 to 6000 oersted.

Abstract: An apparatus is provided for the condensation of sulphur vapor and for the separation of sulphur droplets from a gas flow, preferably from the reaction gas flow from a Claus catalyst. Such apparatus comprises a vessel, a nest of tubes arranged in the vessel between tube plates, pipe connections at the vessel for the supply and discharge of a coolant flowing around the nest of tubes and an inlet pipe connection and an outlet pipe connection for the gas flow at the vessel, upstream and downstream of the said nest of tubes, respectively. Positioned in the vessel is a sulphur separation unit through which the sulphur-containing gas flows and on the surfaces of which sulphur vapor condenses and/or liquid sulphur collects and agglomerates. Sulphur discharge openings are provided in the bottom of the vessel on both the upstream and downstream sides of the separation unit.